Challenging season for organic dairy

Winter grass at Aquila Sustainable Farming’s Riversdale farm ready for calving.

Focusing on soils and non-synthetic fertilisers has been productive for a Southland organic dairy farming company despite a difficult season. Karen Trebilcock reports.

Aquila Sustainable Farming is showing it takes patience, good management, and investment to get soil in a condition where it can cycle nutrients without adding nitrogen fertilisers.

The nine dairy units on six farms in Southland, owned by a German investment fund, have been supplying Open Country’s powder plant at Awarua Bay with organic milk under EU organic standards since late 2018.

And with 5500 cows and 1200 heifers to feed on the 4000ha semi self-contained operation, making sure the soils can produce enough is all important.

Soil consultant for the farms, Soil Matters’ head consultant Rob Flynn, said for the first few years it was about “getting the basics right”.

“Aquila was on a mission – simplifying sustainable food production.

“It had to build from scratch an organic supply chain for all inputs as there was none in place in the South Island at the time capable of producing the projected amounts of milk,” Rob said.

With a stocking rate of between 1.8 and 2.4 cows/hectare, production has averaged between 380 MS/cow to 420 MS/cow.

Rob said it had begun with soil testing.

“When the health of the soil is assessed, the physical, mineral, and biological aspects are all looked at.

“From the beginning, soil tests using the labs at Eurofins were done to determine nutrient requirements in specific areas.

“Recently more extensive soil testing has been done to implement an approach which allows for more fine tuning and also take a close look at the carbon cycling in the soil.”

The farms are run with closed herds and with all young stock grazed together. They are spread across Southland from Kaiwera to Orawia and include irrigated and non-irrigated pastures and a wide variety of soil types, topography, and climate zones.

Rob said potassium, known to be a problem in many Southland soils, was one of the first hurdles.

“One of the products Soil Matters works with is Viafos Potash22.”

NON-SYNTHETIC FERTILISERS

A wide range of non-synthetic fertilisers is available in New Zealand for organic dairy farmers.

These are described as natural products because they are either microbial, animal, or plant by-products or are mined, said BioGrow programme manager (inputs) Robert Murray.

Organic fertilisers are worked on by soil or compost organisms before the nutrients are absorbed by pasture.

Permitted under BioGrow are fertilisers such as dolomite and gypsum, RPR (reactive phosphate rock), natural or elemental sulphur, rock salt and sea salt, naturally mined humates, and potassium sulphate.

He said organic certification includes regular soil testing to assess soil fertility levels and must show either good or generally improving levels.

Restricted fertilisers can also be used if soil or foliar tests show they are required.

These include mined magnesium sulphate (Epsom salts), potassium chloride, langbeinite rock (potassium, magnesium, and sulphur), and trace elements such as soluble boron compounds, sulphates, carbonates, oxides, or silicates including the forms chelated with nonsynthetic agents of cobalt, copper, iron, manganese, molybdenum, selenium, and zinc.

Many solid organic fertilisers are slow release and are usually part of a programme that includes compost, seaweed, and other plant-based preparations that also provide nitrogen.

Ballance Agri-Nutrients science strategy manager Warwick Catto said organic fertilisers tended to cost more as they required additional processing and handling due to strict protocols to avoid crosscontamination.

He said sales of organic fertiliser by Ballance were low and spread throughout the country.

“There are farmers that like to use organic fertiliser although their farm system may not be certified.

“The most common example is farmers who use RPR.”

Left: Soil Matters head consultant Rob Flynn is soil consultant for Aquila Sustainable Farming.

“The slower-release action of Potash22 limits the oversupply of potassium in pastures, avoiding harmful effects on animal health while keeping potassium supplied to growing plants.

“Beside this, other products from the Viafos range are used and the common ones like lime and trace elements.”

He said to get the soil to “cycle” they needed to make sure there was active soil biology and have a functional canopy to turn carbon dioxide into carbohydrates to feed both the cows on top of the ground and the soil life below.

“The N input in this system is low. A higher N input could result in a higher feed production but, from a cost and environmental point of view, it’s better that we aim to utilise the nitrogen in the air.

“The effective use of legumes in the pasture and an active soil biology underneath gives us the nitrogen we need.”

Pastures include mixed swards of ryegrasses as well as plantain, chicory, and different varieties of red and white clovers. Fescue is used instead of ryegrass in some paddocks.

“In the past few years it has been reasonably tough going due to some challenging weather events which every farmer has had to cope with in Southland,” Rob said.

“But unlike other farmers, Aquila, because of its organic status, has had limited opportunity to buy in feed or apply nitrogen to boost feed production.

“However, they have proven to be resilient and that is what it’s about.

“Straight from the beginning it has been a great journey to work with them.

“But the journey has only just begun. The team at Aquila has seen now what they can do when the weather starts to co-operate and are looking forward to even better results in a good growing season.

“It tells them that they are heading in the right direction.”